ABSTRACT

The present study was carried out to determine the effects of screen bottom board trays on reducing ectoparasitic mite Varroa destructor Anderson and Trueman (Acari:Varroidae) populations in honeybee Apis mellifera linguistica (Hymenoptera: Apidae) colonies in the winter, spring and summer season (2013-14). Four honeybee colonies were exposed to oxalic acid (3.2%), thymol (0.5 g) and formic acid (65%) on screen bottom boards in winter, spring and summer seasons. The fourth group had screen bottom board trays but without any chemical. There was a trend of fallen mean number of mites 157±6.28, 97±3.81, 132.75±9.76 and 26±1.68 in winter, 160±20, 149±30, 161.75±18.5 and 27.5±1.04 in spring and 188.25±5.34, 196.25±5.48, 144.25±7.74 and 34.5±4.94 (Mean±SE) in summer, respectively. The average efficacy (%) of the four groups were 86±.58, 66.5±3.93, 75±7.04, 18.25± 10.25 in winter, 77±3.52, 76.75±30, 79±2, 18.25±0.75 in spring and 74.75±1.44, 65.75±1.11, 63±2.04, 18.25±1.11 in summer season, respectively. No queens were lost, and there was no adult honeybee mortality in any of the colonies during the experiment. It can be concluded that screen bottom board trays alone and with soft chemicals in all three seasons effectively control the Varroa mite and can be used without any side effect during all the three seasons.